1. Field of the Invention
The present invention is generally concerned with suspensions of the type used to support overhead electrical power lines, for example.
It is more particularly directed to the situation in which, forming part of a low-voltage electrical power distribution network, the overhead electrical power line to be supported is formed of four insulated cables twisted together, namely three phase cables and one neutral cable.
2. Description of the Prior Art
The suspensions which support an overhead electrical power line of the above kind at each of the posts between which it runs include a support which is fixed to the post, in the form of a bracket or a hook, for example, and a suspension clamp that is adapted to receive the overhead electrical power line and which is suspended from the support either directly, in particular if the support is a hook, or indirectly, for example by means of a shackle, if it is a bracket.
A suspension of the above type is described in French patent 2 478 246 filed Mar. 13, 1980 as application 80 05609, for example.
As described in the above French patent, the suspension clamp has a top part by means of which it is adapted to be suspended from the corresponding support and a bottom part by means of which it is adapted to receive at least a portion of the overhead electrical power line to be suspended, the bottom part having an open cross-section and forming an elongate cradle below the opening, a clamping system associated with the cradle pivoting about an axis parallel to the lengthwise direction of the cradle.
Until now suspensions of the above type have been used only to support the overhead electrical power line concerned, and not for the drawing operation required to install it.
At present this drawing operation is carried out using pay-out pulleys temporarily attached to the posts, one per post, below the corresponding suspension clamps, and it is only afterwards that the overhead electrical power line is transferred from the pay-out pulleys to the suspension clamps.
The pay-out pulleys used for this operation are dedicated to their function and therefore have an opening yoke which makes them relatively complex and costly.
They therefore require a non-negligible investment for their manufacture and maintenance and they are relatively costly in terms of labour to fit and to remove.
Accordingly, it is desirable to be able to dispense with at least some of the pay-out pulleys, given that those at the ends of the overhead electrical power line to be installed, i.e. that immediately downstream of the pay-out cable drum and that immediately upstream of the drawing capstan, can normally only be conserved.
At present only one of the cables constituting the overhead electrical power line is engaged in the suspension clamp of one of the suspensions, namely its neutral cable, which then serves as a supporting cable for the associated phase cables.
It is now desirable for a suspension clamp of the above kind to be able to receive all of the cables of the overhead electrical power line to be supported.